Ribbon conductor set and method

ABSTRACT

A ribbon conductor set and related method of production and installation are provided for electrically interconnecting components in an implantable medical device, such as a heart pacemaker unit or the like. The ribbon conductor set is formed by die cutting and/or stamping a thin plate of conductive material to define a plurality of conductor ribbons supported from a frame. The ribbon set and supporting frame are shaped for seated placement into a fixture to orient the conductor ribbons in predetermined array to extend between electrical components on the fixture, such as between connector blocks and feedthrough terminals of a heart pacemaker unit. The fixture thus supports the conductor ribbons for facilitated connection to the electrical components, such as by welding, after which the resultant subassembly may be further processed as by encapsulation within a cast epoxy head or the like.

BACKGROUND OF THE INVENTION

This invention relates generally to improvements in devices and methodsfor conductively interconnecting electrical components in an implantablemedical device or the like. More particularly, this invention relates toa conductor set and related production and installation method forquickly and easily interconnecting multiple electrical components. Theinvention is particularly designed to facilitate electricalinterconnection of pacemaker lead connector blocks with feedthroughterminals of an implantable heart pacemaker unit or similar device.

Implantable medical devices of the type having electrical circuitcomponents are well known in the medical arts. In one particularlycommon form, the implantable device comprises a pacemaker unit having anappropriate electrical power supply and related control circuitry foruse in electrically stimulating a patient muscle, such as the heart.Such pacemaker unit commonly includes an hermetically sealed case orhousing within which the power supply and control circuitry areprotectively encased, in combination with one or more conductivepacemaker leads extending from the housing to the selected musclestructure within the patient. Feedthrough terminals on the pacemakerhousing accommodate hermetically sealed passage of electrical conductorsto the housing exterior for appropriate connection to the pacemaker leador leads, typically through the use of so-called connector blocks havingset screws or the like for secure lead attachment. The connector blocksand associated feedthrough conductors disposed externally of thepacemaker housing are commonly encased within an hermetically sealedhead structure, such as an insulative head of cast epoxy or the like.

In the past, considerable research and development activity has focusedupon the design of feedthrough terminals for permitting pacing signalsto be transmitted from the hermetically sealed unit housing. Similarly,significant efforts have been directed toward the design of pacemakerlead connector blocks for obtaining a secure yet hermetically sealedelectromechanical connection to pacemaker leads. However, comparativelylittle attention has been directed to the design of conductors andrelated installation methods for electromechanically interconnecting thefeedthrough terminals with the associated lead connector blocks. To thecontrary, available pacemaker units have predominately utilizedelongated wires extending from the feedthrough terminals andindividually shaped by bending for appropriate connection by welding orthe like to the associated connector blocks. Unfortunately, the closeworking space provided in a desirably compact implantable device makesthis wire bending and shaping procedure both tedious and time consuming.Moreover, in pacemaker units having multiple feedthrough terminalconductors, significant attention and skill are required to maintain theconductor wires in sufficiently spaced array to avoid short circuitfailures during pacemaker unit operation.

There exists, therefore, a significant need for improvements in devicesand methods for electrically interconnecting feedthrough terminals withlead connector blocks in a heart pacemaker unit or other implantablemedical device, particularly with respect to permitting the desiredelectrical interconnections to be made quickly and easily with multipleconductors arranged and maintained in spaced relation to prevent shortcircuit failures. The present invention fulfills these needs andprovides further related advantages.

SUMMARY OF THE INVENTION

In accordance with the invention, a ribbon conductor set is provided forfacilitated electrical connection of feedthrough terminals and leadconnector blocks in an implantable medical device, such as a heartpacemaker unit or the like. The ribbon conductor set comprises aplurality of conductor ribbons formed as a set in predetermined number,spacing, and geometry to extend between multiple conductors at one ormore feedthrough terminals and lead connector blocks associated withindividually with the feedthrough conductors. The conductor ribbons areadapted for installation as a group into a pacemaker unit, and in anorientation which accommodates relatively simple connection to thefeedthrough terminals and connector blocks by spot welding or the like.

In accordance with the preferred apparatus and method corresponding withthe invention, the ribbon conductor set comprises the plurality ofconductor ribbons formed from conductive sheet stock by etching and/orappropriate die cutting. The conductor ribbons are arranged in spatialarray to avoid short circuit contact therebetween and further to haveindividualized shapes each adapted for connection between a designatedfeedthrough terminal conductor and associated lead connector block ofthe pacemaker unit. The conductor ribbons are initially supported bynarrow frets from a support frame which is also formed from theconductive sheet stock. A stamping step is typically included to providethe conductor ribbons with a three-dimensional shape as may be requiredfor connection in mutually spaced array to the feedthrough terminalconductors and lead connector blocks. Additional spacer means such as abead of an insulative epoxy and/or a strip of insulative tape may beapplied to the conductor ribbons to maintain the ribbons in spacedrelation during handling and installation.

A fixture is provided for supporting a pacemaker unit housing havingfeedthrough terminals thereon in predetermined positional relation topacemaker lead connector blocks. In this regard, the fixture includeslocator means for receiving and supporting the housing and the connectorblocks at the predetermined relative positions. The ribbon conductor setis then placed over the pacemaker housing and the lead connector blocks,with the support frame and fixture including registration means such asa locator pin received into a frame aperture for accurately positioningthe ribbon set. The individual conductor ribbons each exposed in thismanner for easy access and fixation to the feedthrough terminals andconnector blocks by spot welding or the like. The support frame is theneasily removed from the conductor ribbons by trimming at the frets,whereupon the entire subassembly including the conductor ribbons,connector blocks and feedthrough terminals may be encapsulated within aninsulating head of cast epoxy or the like.

Other features and advantages of the present invention will become moreapparent from the following detailed description, taken in conjunctionwith the accompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a plan view of a ribbon conductor set embodying the novelfeatures of the invention, and illustrating the ribbon conductor setsupported within an integrally formed frame;

FIG. 2 is a plan view of the ribbon conductor set similar to FIG. 1, butillustrating the ribbon conductor set subsequent to die cutting andshaping, and removal of a portion of the support frame;

FIG. 3 is a fragmented elevational view taken generally on the line 3--3of FIG. 2;

FIG. 4 is a perspective view of a fixture for use in mounting the ribbonconductor set into a pacemaker unit or the like;

FIG. 5 is a perspective view of the fixture similar to FIG. 4, butshowing a pacemaker unit housing and pacemaker lead connector blocksmounted within the fixture in predetermined relative positions.

FIG. 6 is an enlarged fragmented perspective view corresponding with anupper region of the fixture as depicted in FIG. 5, but showing theribbon conductor set placed onto the fixture in a position overlying thepacemaker housing and the lead connector blocks;

FIG. 7 is an enlarged fragmented perspective view similar to FIG. 6, andshowing the ribbon conductor set electrically interconnecting the leadconnector blocks with feedthrough terminal conductors, and with thesupport frame for the ribbon set being removed; and

FIG. 8 is a front elevational view of a resultant finished pacemakerunit having the feedthrough terminals, the ribbon conductor set, and theconnector blocks encapsulated within a cast head of a suitableinsulative epoxy.

DETAILED DESCRIPTION OF THE PREPARED EMBODIMENT

As shown in the exemplary drawings, a ribbon conductor set referred togenerally in FIG. 1 by the reference numeral 10 is provided for quicklyand easily interconnecting electrical components in an implantablemedical device, such as a heart pacemaker unit 12 or the like as viewedin FIG. 8. The ribbon conductor set 10 provides a plurality of conductorribbons 14 in a predetermined shape and spatial array in accordance withthe geometry of the electrical components to be interconnected. Thisshaped array of conductor ribbons 14 is supported as a unit or group byan integral support frame 16 for facilitated handling and placement inthe course of connection to the associated electrical components.

The ribbon conductor set 10 of the present invention is designedparticularly for use in an implantable medical device such as a heartpacemaker unit 12 (FIG. 8). In this regard, heart pacemaker units aregenerally known in the art for use in electrical stimulation of theheart muscle to regulate patient heartbeat in a controlled manner. Thepacemaker unit 12 normally includes an appropriate power source andrelated electronic circuitry encased within a compact, hermeticallysealed housing or case 18 adapted for implantation directly into thebody of a patient at a selected convenient location The unit produces atimed sequence of pacing pulses which are coupled to one or moreconductive pacemaker leads 20, with the illustrative drawings depictingthe pacemaker unit 12 to include a pair of pacemaker leads 20 forso-called duplex mode operation. The pacemaker leads 20 extend from theunit housing 18 for implantation of their distal ends (not shown) intotarget muscle tissue to be stimulated.

As shown best in FIG. 8, the pacemaker unit 12 includes a head 22 on theunit housing 18, wherein the head 22 includes means forelectromechanically anchoring the pacemaker leads 20 in conductiverelation with the pacing signals generated by the circuitry componentswithin the housing 18. More specifically, the pacemaker housing 18defines a relatively flat mounting platform 24 at one edge thereof. Oneor more so-called feedthrough terminals 26 project upwardly from thisplatform and provide hermetically sealed structures of a type known inthe art for passing electrical conductors from the interior of thehousing 18. The illustrative drawings show a pair of feedthroughterminals 26 each including a pair of short upstanding conductors 28,thereby providing a total of four conductors 28 for use in duplex modepacemaker unit operation. These feedthrough terminal conductors 28 arerespectively connected by means of the ribbon conductor set 10 of thepresent invention to a corresponding set of four connector blocks 30adapted for electromechanical connection to the pacemaker leads 20.Subsequent to electrical interconnection of the feedthrough terminalconductors 28 with the connector blocks 30, as will be described in moredetail, these components are encapsulated within a block of insulativeepoxy material or the like which is cast in place to define the head 22maintaining the various components in the desired hermetically sealedand predetermined interspatial relation.

The apparatus and method of the present invention is designed tofacilitate the process of interconnecting the feedthrough terminalconductors 28 with the connector blocks 30. More particularly, theribbon conductor set 10 provides a preshaped and prespaced array ofconductive elements which can be handled as a unitary set or group forrapid yet accurate placement and appropriate connection by resistancespot welding or the like. The ribbon set 10 is adapted forcost-efficient manufacture by die cutting and/or stamping processes toyield detailed yet reproducible ribbon shapes in conformance with thegeometry of the feedthrough terminals and connector blocks to beinterconnected. Importantly, when the ribbon set is mounted in place,the individual conductor ribbons 14 are maintained in sufficient spacingto substantially eliminate risk of short circuit failures.

With reference to FIG. 1, the ribbon conductor set 10 is formed fromsheet stock of a suitable conductive material to include the set ofconductor ribbons 14 carried within the surrounding support frame 16. Asshown in the initial stages of formation, the support frame 16 isgenerally coplanar with the conductor ribbons 14, with each ribbon 14having an individualized elongated shape supported at its opposite endsby a pair of narrow frets 34 on the support frame 16. In a preferredmethod of formation, this frame and ribbon set combination is formed byetching thin sheet stock of stainless steel or platinum alloy or thelike to produce the desired ribbon pattern, wherein this etched sheetstock may have a thickness on the order of a few thousandths of an inch.Alternately, cutting and/or stamping processes may be used. Desirably,the support frame 16 includes one or more large ports 36 formed thereinto permit accurate placement into process tools and fixtures.

FIGS. 2 and 3 illustrate the ribbon conductor set 10 subsequent to astamping and cutting process step for shaping the individual conductorribbons 14 to an appropriate three-dimensional geometry. Morespecifically, the ribbon set can be seated into an appropriate die toolfor shaping each ribbon 14 to include one or more bends deviating fromthe plane of the support frame 16. FIG. 3 illustrates all four ribbons14 to include a common rearward bend 38 in close association with areturn bend 40. In addition, FIG. 2 shows one of the ribbons 14 toinclude a generally semicircular bend 42 for clearance with afeedthrough terminal 26, as will become more apparent. During this diestamping step, a portion of the support frame 16 is desirably removed bytrimming the frame at points 43 and 44, and by severing the frets 34 atone common end of the conductor ribbons 14. As a result, the conductorribbons 14 project generally in somewhat cantilevered relation from theremaining portion of the support frame 32 which remains connected to theribbons by means of the remaining frets 34.

The conductor ribbons 14 are desirably provided with additional supportmeans to maintain the inter-ribbon spacing and to minimize risk ofribbon damage during subsequent handling. For example, as shown in FIG.3, an elongated bead 46 of epoxy or the like may be placed and curedalong the conductor ribbons 14 such as at the inboard side of the bend38 to support the ribbons with respect to each other. Alternatively, orin addition, a strip of tape 48 such as insulating tape of Dapton filmor the like may be used as a temporary support for the fragile ribbons14.

A fixture 50 is depicted in FIGS. 4-7 for use in supporting the variouscomponents in a convenient arrangement during placement and mounting ofthe ribbon conductor set 10. More particularly, the illustrative fixture50 includes a base plate 52 which cooperates with a short upstanding andgenerally U-shaped base wall 54 to define an open-sided cavity 56 (FIG.4) for receiving the housing 18 of the pacemaker unit 12. Aspring-loaded foot 58 is centrally located along the base wall 54 at aposition opposite the open side thereof, and can be suitably manipulatedby a knob 60 or the like and related spring 61 to press against the unithousing 18. This pressing action of the foot 58 advances one side edgeof the housing platform 24 into seated relation with a short upstandingrib 62 on the base plate 52, thereby positively and firmly locking theunit housing 18 in a predetermined orientation within the fixture 50(FIG. 5). Such placement of the unit housing 18 additionally positionsthe feedthrough terminals 26 and their respective short protrudingconductors 28 at predetermined locations within the fixture.

The connector blocks 30 are also mounted into the fixture 50 atpredetermined positions. In this regard, as shown in FIG. 5, theconnector blocks 30 are traditionally provided in interconnected pairswith each connector block having a flat rear face 30' with a shallowthreaded bore 29 formed therein These threaded bores 29 are intended forsubsequent reception of set screws (not shown) for use in lockingconnection to the pacemaker leads 20. At this stage, however, thethreaded bores 29 in the connector blocks 30 are open and provideconvenient receptacles for short positioning pins 63 on the fixture baseplate 52, such that the connector blocks 30 are predeterminablypositioned relative to the feedthrough terminals 26. Additionalanchoring of the pairs of connector blocks 30 may be provided bytemporary insertion of lead pins 64 into the connector blocks, whereinthese lead pins 64 are conveniently mounted on the fixture forretractable movement limited by enlarged pin spools 66 adapted to abut apair of raised stops 68 and 70.

With the pacemaker unit housing 18 and the connector blocks 30 in place,the ribbon conductor set 10 is easily placed in overlying relation overthe pacemaker components. A short locator pin 72 on the fixture 50 isadapted for reception into a mating aperture 74 in the support frame 16to predetermine the position of the ribbon set (FIG. 6). In thisposition, the free ends of the individual conductor ribbons 14 aligneasily and accurately with the respective feedthrough terminalconductors 28, and the opposite fret-supported ends of the ribbons 14align with the respective connector blocks 30. In this orientation, bothends of each ribbon 14 can be attached quickly and easily to theassociated components by resistance spot welding or the like, and theremainder portion of the support frame 16 can be removed quickly andeasily by severing at the frets 34. The strip of support tape 48, ifused, may be removed at a convenient time typically subsequent to ribbonattachment to the underlying components.

The resultant head subassembly, including the connector blocks 30interconnected via the conductor ribbons 14 with the feedthroughconductors 28, provides an accurate and highly attractive electricalinterconnection. The pacemaker unit 12 including this head subassemblyis removed from the fixture 50 and appropriately processed to cast theepoxy head 22. This head 22, as viewed in FIG. 8, encapsulates theelectrical components with an insulative and hermetic seal material.This epoxy head further supports the components in the desiredpredetermined spatial relation, and in a manner which is fullycompatible with the epoxy bead 46 (FIG. 3) used to support the ribbons14 during processing.

The ribbon conductor set 10 thus provides a simple apparatus and methodfor facilitated and accurate electrical interconnection of feedthroughterminals and lead connector blocks in a heart pacemaker or the like.The conductor ribbons 14 are preformed in a manner consistent witheconomical production processes, and in a manner permitting handling asa unitary group during installation procedures.

A variety of modifications and improvements to the ribbon conductor set10 and related installation method will be apparent to those personsskilled in the art. Accordingly, no limitation on the invention isintended by way of the foregoing description and the accompanyingdrawings, except as set forth in the appended claims.

What is claimed is:
 1. A ribbon conductor set for interconnectingelectrical components in an implantable medical device, said ribbonconductor set comprising:a plurality of conductor ribbons formed as aset in a predetermined number, shape, and spacing; a support frameincluding means for removably supporting said conductor ribbons as agroup, said conductor ribbons and said support frame being integrallyformed from common sheet stock of a selected conductive material; andspacer means for connection to said conductor ribbons to maintain aselected spacing therebetween, wherein said spacer means comprises anepoxy bead.
 2. The ribbon conductor set of claim 1 wherein said supportframe generally surrounds said conductor ribbons.
 3. The ribbonconductor set of claim 1 wherein said conductor ribbons are generallyelongated in shape, and wherein said means for removably supporting saidconductor ribbons comprising a plurality of frets for respectivelyconnecting generally adjacent ends of each of said conductor ribbonsdirectly to said support frame.
 4. The ribbon conductor set of claim 1wherein said spacer means is mounted onto said conductor ribbonsgenerally at a common bend point defined by said conductor ribbons. 5.The ribbon conductor set of claim 1 wherein said means for removablysupporting said conductor ribbons comprises a plurality of relativelynarrow frets.
 6. The ribbon conductor set of claim 5 wherein each ofsaid conductor ribbons is directly supported from said support frame byat least one of said frets.